Sweetening and stabilizing hydrocarbon oils



Patented Apr. 6, 1954 UNITED STATES ATENT OFFICE SWEETENING AND STABILIZING HYDROCARBON OILS Johan C. D. Ousterhout grey, Port Arthur, Tex. Company, New York, N.

Delaware and Gwendolyn D. Pinassignors to The Texas Y., a corporation of 11 Claims.

This invention relates to the treatment of hydrocarbon oils containing mercaptan sulfur and contemplates treating the oil with an organic metallic salt in combination with certain mercapto-alkylbenzimidazoles.

Organic metallic salts such as copper naphthenate are known to have a sweetening effect on hydrocarbon oils. We have now discovered that the addition of mercapto-alkyl-benzimidazoles greatly promotes the sweetening reaction. The mercapto-alkylbenzimidazoles in themselves have only a very slight sweetening effect but when the oil is contacted with both the organic metal salts and the mercapto-alkyl-benzimidazole, the sweetening effect is greatly increased over that accomplished by the organic metal salt alone. The treatment with the combined materials thus constitutes an advantageous additive sweetening process.

In accordance with the invention the hydrocarbon oil is contacted simultaneously with an organic metal salt such as salts of copper, cobalt, lead or zinc, particularly oleates and naphthenates, and with a mercapto-alkylbenzimidazole. The substituted mercapto-benzimidazoles are quite soluble in hydrocarbon and very eiiective in the combination sweetening process. The mercapto-a1kylbenzi1nidazoles effective in the process include 2 mercapto-mono-alkyl-benzimidazoles such, for example as 2 mercapto-5-tamylbenzimidazole and 2 v mercaptoi-t-amylbenzimidazole. Instead of compounds with the amyl alkyl group, other compounds such as methyl, ethyl, propyl, butyl, hexyl, octyl, decyl, and dodecyl, are adapted for the practice of the invention. j

The organic metal salts while possessing good sweetening properties have the disadvantage of accelerating gum formation. We have found, however, that the tendency toward gum formation may be inhibited without materially depreciating the sweetening effect by the addition to the treating materials of an N-salicylalamino alkane and in accordance with the invention the oil is subjected to the simultaneous action of the organic metal salt such as copper naphthenate or cobalt naphthenate, the mercapto-alkylbenzimidazole and N-salicyclalamino alkane, particularly a polysalicylalamino polyalkane such as N,N'-disalicylal-1-2-diaminopropane.

A further feature of the invention involves the addition to the combination of treating reagents of a material adapted to stabilize the oil as regards oxidation or gum formation and the material preferably employed is one that possesses a sweetening property as well as a stabilizing one such as a para-phenylenediamine. In accordance with the invention, therefore, the oil is contacted with the organic metal salt, the mercapto-alkylbenzimidazole, the N-salicylalamino alkane and a para-phenylenediamine such as an N,N'-dialkylpara-phenylenediamine, particularly N,N-disecbutyl-para-phenylenediamine, to efiect both sweetening and stabilization of the oil. If desired the para-phenylenediamine may be added to the oil subsequent to the contacting with the other materials.

The invention is adapted particularly for the treatment of hydrocarbon oil which although sour and yielding a positive reaction in the doctor test contains a relatively small mercaptan content. Thus, the invention is especially adapted for the treatment of such stocks as light naphthas from fluid catalytic cracking operations and low mercaptan straight run naphtha which can be rendered completely sweet and stable against oxidation without other treatment or addition of inhibitors. The process is also adapted as a finishing treatment to sweeten and stabilize stocks which have previously received treatment for the removal of mercaptans such as alkaline treatments.

It is to be emphasized that the process is essentially an additive treating process and does not require large quantities of treating materials. Thus, the quantities required are far less than the stoichiometric quantity on the basis of the mercaptan content. The amount of organic metal salt required will generally not amount to over T 6 of the stoichiometric. Being an additive process it possesses a particular advantage in that it does not require the usual agitators or reaction vessels commonly employed in treating processes. The distillate to'be treated can be taken directly from the stills or from a preceding treating system and sent to tankage and the process of the invention may be applied by simply introducing the additives into the transfer line. The materials introduced are soluble in the hydrocarbon and the mixing in the pipe and in the tank where the distillate is received is adequate to effect the desired dispersion of the treating materials in the oil.

The amount of the salicylalamino alkane which will offset the gumming tendency of the organic metal salt while still permitting the desired sweetening eiiect is at a ratio of salicylalamino alkane to organic metal salt of about 1:1 and at least not lower than about 0.75:1. The efiective quantities of the mercapto-alkylbenzimidazole 3 are in the order of 5 to pounds per thousand barrels of oil treated.

In an example of the invention a cracked naphtha was treated with 10 pounds per thousand barrels of oil of N,N disecbutyl paraphenylenediamine, 5 pounds per thousand barrels of copper naphthenate, and 10 pounds per thousand barrels of 2 mercapto-fi-t-amylbenzimidazole and the product was negative to the doctor test after overnight standing.

In a second example with the same quantity of the para-phenylenediamine, with 2 pounds per thousand barrels of copper naphthenate and with 5 pounds per thousand barrels of the amylbenzimidazole, the product was negative to the doctor test after overnight standing.

It is to be observed that air or oxygen-blowing is not necessary for carrying out the process and, in fact, the process can be conducted satisfactorily in closed systems in which practically no air is present. However, air-blowing has a tendency to increase somewhat the rate of sweetening. The presence of traces of alkali metal Joy droxide accelerates the rate of sweetening. Thus, it is advantageous when employing the herein-described process to completely sweeten and stabilize an oil previously subjected to a caustic treatment, to avoid a complete removal of the caustic from the preceding treat and permit traces of caustic to remain in the oil which is passed to the final sweetening and stabilizing treatment.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. The method of treating hydrocarbon oils containing mercaptan sulfur to effect the sweetening thereof that comprises contacting the oil with an organic metal salt and a mercapto-alkylbenzimidazole.

2. The method of treating hydrocarbon oils containing mercaptan sulfur to eifect the sweetening thereof that comprises contacting the oil with copper naphthenate and a substituted mercapto-alkylbenzimidazole.

3. The method of treating hydrocarbon oils containing mercaptan sulfur to effect the sweetening thereof that comprises contacting the oil with copper naphthenate and 2 mercapto-5-tamylbenzimidazole.

4. The method of treating hydrocarbon oils containing mercaptan sulfur to effect the sweetening thereof that comprises contacting the oil with an organic metal salt, a mercaptoalkylbenzimidazole and an N-salicylalamino alkane.

5. The method of treating hydrocarbon oils containing mercaptan sulfur to effect the sweetening thereof that comprises contacting the oil with copper naphthenate, a substituted mercapto-alkylbenzimidazole and a polysalicylarnino alkane.

6. The method of treating hydrocarbon oils containing mercaptan sulfur to effect the sweetening thereof that comprises contacting the oil with copper .naphthenate, 2 mercapto-S-t-amylbenzimidazole and N,N-disa1icylal-1-2-diarninopropane.

'7. The method of treating hydrocarbon oils containing mercaptan sulfur to effect the sweetening and stabilization thereof that comprises contacting the oil with an organic metal salt, a mercapto-alkylbenzimidazole and a para-phenylenediamine.

8. The method of treating hydrocarbon oils containing mercaptan sulfur to effect the sweetening and stabilization thereof that comprises contacting the oil with copper naphthenate, a substituted mercapto-alkylbenzimidazole and an N,N-dialkyl-para-phenylenediamine.

9. The method of treating hydrocarbon oils containing mercaptan sulfur to effect the sweetening and stabilization thereof that comprises contacting the oil with copper naphthenate, 2 mercapto5-t-amylbenzimidazole and N,N'-disecbutyl-para-phenylenediamine.

10. The method of treating hydrocarbon oils containing mercaptan sulfur to effect the sweetening and stabilization thereof that comprises contacting the oil with copper naphthenate, 2 mercapto-5-tamylbenzimidazole, N,N-disalicylal-1-2-diaminopropane and N,N-disecbutylpara-phenylenediamine.

11. The method of treating hydrocarbon oils containing mercaptan sulfur to effect the sweetening and stabilization thereof that comprises contacting the oil with an organic metal salt, a substituted mercapto-alkylbenzimidazole, a polysalicylamino alkane and an N,N'-dialkyl-paraphenylenediamine.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,228,041 Yabroff et a1 Jan. 7, 1941 2,616,831 Rosenwald Nov. 4, 1952 2,642,396 Roddy June 1, 1953 FOREIGN PATENTS Number Country Date 956,851 France Sept. 5, 1951 

1. THE METHOD OF TREATING HYDROCARBON OILS CONTAINING MERCAPTAN SULFUR TO EFFECT THE SWEETENING THEREOF THAT COMPRISES CONTACTING THE OIL WITH AN ORGANIC METAL SALT AND A MERCAPTO-ALKYLBENZIMIDAZOLE. 